1. Field of the Invention
The present invention relates to a Sphingomonas sp. MD2 strain (KCTC 11845BP), a composition including the strain for decomposing methane or odor-producing compounds, a biocover or biofilter including the composition, a method for decomposing methane or odor-producing compounds using the composition, a system for decomposing methane or odor-producing compounds using the biocover or biofilter, and the use of the strain for decomposing methane or odor-producing compounds.
2. Description of the Related Art
Under anaerobic conditions, organic materials are finally converted into methane and carbon dioxide by microbial decomposition with the release of odor-producing compounds such as hydrogen sulfide, methanethiol (MT), dimethyl sulfide (DMS), ammonia, amine, fatty acids or the like. Therefore, organic waste treatment facilities and processes such as landfills, food waste treatment facilities, anaerobic digestion, and livestock barns are known as the foremost sources for the emission of methane and producing odor concurrently. Of them, landfills are one of the most foremost sources of methane and odor emission, and there were 227 landfills in Korea in 2007 (Ministry of Environment, Resource and Recirculation Bureau, 2007), and the total area of landfills and the volume of landfills were 29,213,000 m2, and 379,416,000 m3, respectively. Evaluated by the gas treatment capacity of these landfills, the landfills equipped with facilities capable of capturing emitted gas for the extraction and subsequent reuse as alternative energy of high concentrations of methane account for only 4% (10 landfills) of the total number of landfills, and most landfills (199 landfills, 89%) emit landfill gas directly into the atmosphere.
Methane is a major greenhouse gas, second only to carbon dioxide, and accounts for 18% of radiative forcing. Since methane concentration in the atmosphere has more than doubled since the industrial era, many studies have focused on the sources and sinks for methanogens or related microorganisms (Bodelier et al., FEMS Microbiol. Ecol. 52, 163-174, 2005). In addition, prior studies have focused on the distribution and diversity of methane-oxidizing microbial communities that play an important role in the global carbon cycle (Bodelier et al., FEMS Microbiol. Ecol. 52, 163-174, 2005).
Landfills are the largest source of methane emissions, and are estimated to account for approximately 35% of anthropogenic methane emissions in US, and 5˜10% of global methane in the atmosphere (IPCC, 2001; Stern et al., Waste Manage. 27, 1248-1258, 2007). The representative technologies associated with reduction of methane gas generation during waste treatment are landfill gas capturing and resource recycling technologies, but it is difficult to apply these technologies to inefficient landfills and in cases of emission of low concentrations of methane.
The odor emitted from organic waste treatment facilities such as landfills, food waste treatment facilities, and livestock waste treatment facilities is also a main cause of civil complaints. Reportedly, civil complaints about odor emitted from organic waste treatment facilities account for 60% of the civil complaints about odor in public facilities in 2006 (Ministry of Environment, Air Quality Management Bureau, 2006), and 32% of the civil complaints about the odor emitted from organic waste treatment facilities was related to landfill odors (Ministry of Environment Air Quality Management Bureau, 2006). Landfill odors are produced by a variety of sources. Of them, hydrogen sulfide is the primary cause of odor, and its concentration and emission rate are known to be 0.7˜1463.5 mg/m3, and 0.3˜633.5 mg·m−2·h−1, respectively. According to a recent survey of landfill odors in Korea, terrible odor is caused by the emission of landfill gas through cracks or holes in landfill layers and cover layers, and the odor concentration in the landfill gas that was emitted through the cracks at the surface of landfill cover was approximately 17,000 as a dilution ratio, and the concentration of hydrogen sulfide was 400,000 ppb or higher. When waste is compressed by a compressor, landfill gas moves to the outer slope of the landfill. Thus, odor management for the outer slopes of landfills is also needed.
Odor management in organic waste treatment facilities or processes, such as landfills, is mainly conducted by odor measurement and monitoring, with passive management such as the use of deodorizers only being conducted for odor suppression. Given the future compulsory regulatory disclosure of odor management capability and equipment by public works facilities such as landfills, manure treatment facilities, and other organic waste treatment facilities, there is an existing need for novel technologies addressing the root sources of odor.
Recently, various odor reduction techniques such as the use of landfill covers having odor reduction effects, placement of on-site biofilters on cracks, and placement of portable biofilters in landfill gas wells have been proposed. However, the techniques are not actively utilized for odor reduction, because of their high cost and low efficiency. In particular, odor management techniques have been very actively developed as compared with methane reduction techniques, and a variety of odor management and control techniques such physical, chemical, biological, and hybrid techniques have been developed and commercialized. However, with respect to economic aspects such as installation cost and running expense, the conventional odor reduction techniques are not suitable in application to large areas including landfills. Therefore, the issues resulting from odor in these sources have not been solved yet.
Accordingly, reduction of both odor and methane emissions will create a new economic effect of earning carbon emission credits corresponding to the methane reduction, which offsets the costs required for applying only the odor reduction techniques. It is also expected that the efficiency of land use can be improved by solving the odor byproduct of waste treatment facilities such as landfills, which can contribute to national industrial competitiveness through the bolstering or creation of related industries.
Given this background, the inventors of the present invention have made many efforts to develop a technique for removing both methane and odor that are generated from landfills or the like, and they found that a novel Sphingomonas sp. strain is able to remove methane and odor-producing compounds concurrently, thereby completing the present invention.